Transformer for electric welding



Aug.3,1926. 1,594,891

G. A. LUTZ TRANSFORMER FOR ELECTRIC WELDING Filed March 25, 1925 2 sheets-Shea; 1

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A. LUTZ TRANSFORMER FOR ELECTRIC WELDING Filed March 23, 1925 2 Sheets-Sheet 2 5:::IIIIIIIIIIIII -II I I I n I BE??? m M T N Nu m N AF e L 7 m B fa Patented Aug 3, 1926.

UNITED STATES.

1,594,891 PATENT OFFICE.

GEORGE A. LUTZ, OI CRANFORD, NEW JERSEY, ASSIGNOR TO AMERICAN CIRCULAR LOOM COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

TRANSFORMER FOR ELECTRIC WELDING.

Applicationflled March 23, 1925. Serial No. 17,625.

My invention relates to improvements in the class of electric transformers in which the primary and secondary together with the contact terminal electrodes of the secondary all rotate as a unit, such transformers being particularly useful in the art of electric welding and for analogous metal heating purposes. In such transformersthe electric current is led to the rotating primary through suitable brushes and collector rings and during such rotation of the transformers the secondary current passes between therotary terminal contact electrodes of the secondary and the metal in contact therewith to heat the same at the contact point. Some of the known rotary transformers have continuous roller contact electrodes as the terminals of secondaries extending around the whole-periphery of the roller, whereby every part of the periphery will come in contact with the metal to be heated as the roller contacts rotate. Such secondary roller contacts become highly heated with a tendency to distortion of the rollers.

An object of my invention is to provide in a rotary transformer secondary terminal contact electrodes in such a way that when they become highly heated the peripheral portions thereof may expand uniformly and resist'distortion due to the heat of the electrodes.

' In carrying out my invention Iprovide a rotary transformer with separate terminal electrodes in annular form having discontinuous contact peripheries provided by means of recesses extending through the surfaces thereof, whereby the peripheral portions of the terminal electrodes between the several recesses may expand freely to reduce or prevent distortion thereof and the metal at the edges of the recesses will assist in the feeding of a tube against the terminal electrodes.

My invention also comprises novel details of improvement that will be more fully hereinafter set forth and then pointed out in the claims.

Reference is to be had to the accompanying drawings forming a part hereof, wherein Fig. 1is a side elevation illustrating a rotary transformer equipped with my invention;

Fig. 1 is a detail section on line 1 in Fig. 1;

issued December 18, 1923, to H.- E. Snodgrass and Thomas M. Hunter, although my improvement may be utilized in a rotary electric transformer of different construction from that of said Letters Patent. In the drawings the numeral 10 indicates a frame of the transformer provided with standards 10 having bearings 13 in which is journaled an operating shaft 11 which, when the transformer is to be air-cooled, is preferably provided with a central passage 12, to which air may be supplied through a pipe 16. The shaft may be vertically adjustable by means of screws and nuts at 14 in a known way,

and may be driven from any suitable source of power through suitable connections, shown as a sprocket wheel 15, although the transformer may be driven by the passage of work in connection with the rotary contact terminal electrodes hereinafter described. The end of shaft 11 is preferably provided with a supporting member 17 which is provided with a central opening screw threaded at 18 to engage the screw threaded end of the shaft 11, the supporting member abutting against the flange 19 on shaft 11. The transformer, which is shown as rotatable and which is preferably secured to the member 17, comprises a secondary 20 which may be conveniently formed of cast metal and which in the form shown comprises a shell having a face plate 21 electrically connected to and preferably integral with one end of an axis 22 extending axially through the transformer, the central passage 22' communicating with the hollowshaft 11. The secondary shell also comprises a cylindrical part 23 preferably integral with the face plate 21 and preferably formed with openings 24 for ventilating purposes. opposite side of the secondary shell is closed central opening 27 which is of Slightly greater diameter than the axis 22 so that the plate, 25 is spaced from said axis sufficiently to insulate the same therefrom. A core 28 for the transformer, preferably annular in form, is located within andentirely enclosed by the shell of the secondar of the trans former, which constitutes a c ambered body, the shell of the secondary of the transformer being electrically continuous in the direction of the generated current throughout the region "of the c0re,-i. e. without the inner side of the core. The secondary completel enclosing the core and primary, as describe may be considered as made up of an indefinite number of conductors symmetrically arranged with reference to the axis thereof providing for a magnetic, mechanical and electric balance under load conditions and this balance is not affected by the rotation of the transformer. It will be apparent that for each assumed conductor loop of the secondary around the core and primary there will be a loop of equal length on the opposite side of the axis of the transformer and symmetrically arranged with reference to said axis. The core may be held in position withinthe secondary b bolts 29 extending through the core and t rough the plates 21 and 25 respectively. The core 28 is covered by suitable insulation 30 and is surrounded by a primary winding 31, which may be in the form of a flat ribbon wound edgewise around the core. When the winding is made in ribbon form and is formed before the winding operation it is deemed necessary to provide an opening in the core which is closed after the winding is placed in position, as set forth in Letters Patent No.

1,478,262 aforesaid. Further details of construction of the form of core and its laminations which may be used are set forth in said patent. The secondary of the trans former is secured to the supporting member 17 by bolts or screws 33, suitable insulation being interposed between the plate 21 of the seconda and the supporting member 17, suitable insulating material also being interposed between the bolts 33 and themember 17.

Current is supplied to the primary of the transformer by collector rings 34, 34, secured to. the face plate 21 by bolts 35, suitable insulation being interposed between the bolts and the plate. The terminals 36, 37 connect the primary terminals to therespective collector rings. Alternating current is carried to the collector rings from any suitable source of suppl by brushes 38 suitably disposed around t e rings.

The foregoing parts represent corresponding parts illustrated in the aforesaid Letters Patent No. 1,478,262, and the mode of operation is the same as set forth in said Letters Patent.

At 39 and 40 are a pair of annular secondary terminal electrodes providing. rotary contacts having interrupted peripheral contact surfaces to engage the metal to be welded or heated. In the example illustrated the secondary terminal electrodes 39, 40 are electrically connected to the axis 22 and to the plate 25 respectively, and the plate 25 may be provided with a plurality of bosses 25" against which the contact or electrode member 40 is seated, thereby providing ventilating spaces 25 between the member 40 and the plate 25. Insulation at 41 may be interposed between the contact electrode members 39, 40 whereby they are separated, and they ma be secured together by screws 42 insulate from theelectrode terminal 39, although said terminal electrodes 39, 40 may be insulated by means of an air space therebetween by omitting the insulation 41. The electrode member 39 is shown secured upon the axis 22 by means of interposed screw threads, and a nut a on said axis retains said parts together.

The peripheral portions of the electrode terminals 39, 40 are adapted to engage the -metal to be welded or heated during rotaprovide the terminals with discontinuous or spaced contact peripheries, whereby when the metal of the electrode terminals expands by reason of heat the peripheral contact surfaces 39, 40*, between corresponding spaced recesses 39, 40* may expand in an annular direction but without one section engaging another, so that the tendency to'distortion of the peripheral surfaces of the terminal electrodes is reduced or prevented, and such peripheries will retain their original and intended contours to a greater extent than would occur were the terminal electrode peripheries in continuous roller or wheel-like formation, such as set forth in the Letters Patent No. 1,478,262 aforesaid. The metal of each electrode 39, 40, I have illustrated,

is electrically continuous throughout, in a unitary structure, such as a solid or single piece of metal having the peripheral recesses which produce the discontinuous contact sections referred to. The discontinuous peripheral portions of the terminal electrodes 39, 40, such as the disconnected sections thereof, serve to assist in cooling such surfaces during use.

I have shown the terminal electrodes as adapted for welding longitudinal seams of tubes A. For such purpose the terminal electrodes 39, 40 are provided with a peripheral groove-like formation corresponding to a similar groove in the peripheries of roll B against which the tube bears for welding' the latter. The roll B is shown mounted on a shaft 43 journaled in bearings at 44 upon the brackets 10. The tube may be guided in any suitable or well known way or as shown in Letters Patent No. 1,478,262 aforesaid, in such a manner that the seam of the tube to be welded will register with the space between the terminal electrodes 39, 40, such as in register with the space or the insulation 41 therebetween.

In the form illustrated in Figs. 1, 2, 3 and 6 the recesses 39, 40 of the terminal electrodes are shown located in the material of the electrodes at anangle to the axis of the electrodes, such as in a diagonal direction respecting such axis, in such a way that the recesses of one terminal electrode oppose the metal of the other terminal electrode, whereby one peripheral section oPone terminal electrode opposes portions 'of two peripheral sections of the other terminal electrode. Instead of the recesses 39, 40. extending at an angle to, the axis of the terminal electrodes said recesses may be disposed parallel to such axis, as shown in Figs. 4 and 7. Instead of the peripheries of the terminal electrodes 39, 40 being grooved such surfaces may be plane or flat surfaces or in the nature of rollers, as illustrated in Figs. 5, 6 and 7, which would adapt the terminal electrodes to operate ,upon sheets of metal 0 to be welded or heated. The transformer will rotate during the feeding of i the metal to be welded or heated either by reasonof direct rotation of shaft 11, or if that is not operated by power then by reason of feeding of the tube A or other work in contact with the terminal electrodes 39, 40

which will cause their rotation as well as rotation of the transformer bodily. An advantage of my improvement is that the edges of the metal at the peripheral recesses 39, 40", of the terminal electrodes will engage the surface of tube A in such a way as to assist in maintaining feeding relation between the tube and the electrodes and resist the tendency to slipping therebetween.

In accordance with the construction set forth, during the operation of welding or heating metal in contact with the terminal electrodes 39, 40 a relatively high voltage, low current of the primary is changed to a low voltage, high current in the secondary which terminates in the contact members or terminal electrodes 39 and 40, and when the metal passes through the machine the current flows from the metal on one side of the seam to the metal on the other'side of the 7 seam, thereby welding the metal. The current is carried to the metal at a point of opposite sections of the periphery of the electrodes, which point advances around the periphery of the electrodes as the transformer 7 rotates, and when one of the recesses 39 or 4E0 opposes the metal or tube there may be a flow of current from one of the peripheral sections of the electrode terminal 39 to one or the other of the adjacent spaced peripheral sections of the terminal electrode 40, but not at the recess, and vice versa, according to the width of the recesses, at the spot or point on the metal or tube momentarily opposed by the peripheral recess of S the corresponding terminal electrode, in the nature of spot welding, but this would not interfere with sufficient welding of the seam of the tube or the welding of superposed metal plates for some purposes.

The electricaladvantages of the form of construction of the transformer I have illustrated in connection with my improvement have been set forth in Letters Patent- No./1,478,262 aforesaid. Myimprovement is not limited to use inconnection with the particular construction of such transformers since the same may be used in other suitable arrangements of primary and secondary in a rotary transformer which will produce induced current in the secondary for transmitting through the annular terminal electrodes 39 and 40 having the spaced periphera-l recesses.

Having now described my invention what 1 I claim is 2- 1. In an electrical transformer a pair of unitary annular terminal electrodes secured together side by side and insulated from one another, said, electrodes having peripheral 1 recesses providing spaced peripheral contact sections." 1 Y 2. In an electrical transformer a pairof annular terminal electrodes secured together side by side and insulated from one another, 1 said electrodes having peripheral recesses providing spaced peripheral contact sections. said recesses extending at an angle respecting the axis of the terminal electrodes.

3. In an electrical transformer a pair of concentric annular terminal electrodes secured together side by .side and insulated from one another, said electrodes having peripheral recesses providing spaced "peripheral contact sections, the recesses of one electrode being spaced with respect to the recesses of the other electrode, a peripheral contact section of one electrode opposing portions of two peripheral contact sections of the other electrode.

4. In an electrical transformer a pair of concentric annular terminal electrodes secured together side by side and insulated from one another, said electrodes having pe- 5 ripheral recesses providing spaced periph-- eral contact sections, the recesses of one electrode being spaced with respect to the recesses of the other electrode, a peripheral contact section of one electrode opposing portions of two peripheral contact sections of the other electrode, said recesses extending atan angle respecting the axis of the GEORGE A. LUTZ.

terminal electrodes. 

